Banca de QUALIFICAÇÃO: JOSE LUIZ DE SOUZA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSE LUIZ DE SOUZA
DATE: 15/07/2021
TIME: 09:00
LOCAL: ON LINE
TITLE:

SYNTHESIS OF V2O5 THROUGH MICROWAVE RADIATION WITH POTENTIAL APPLICATION IN LITHIUM-ION BATTERIES

KEY WORDS:

Vanadium Oxide, Hydrotermal, Microwave, Synthesis

PAGES: 50
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SUMMARY:

Due to the increase in electronic devices and, consequently, the greater demand for ion-lithium batteries, low-cost, alternative as cathode materials with high energy density have been extensively investigated. In this scenario, V2O5 must be highlighted as  a theoretical specific energy of 294 mAhg-1, which is superior to cathodic materials  popularly used. However, factors such as its low structural stability, low diffusion coefficient and low electrical conductivity make the search for new synthesis processes for this oxide intermittent. Thus, the present research aimed to obtain V2O5 structures by two distinct syntheses. In the first one, the vanadium oxide was distributed by hydrothermal treatment using the ammonium metavanadate, NH4VO3, as a precursor. Characterization studies indicated a formation of orthorhombic V2O5 with crystalline structure. Morphological characterizations showed a compact, heterogeneous and not very porous structure. This fact may help to explain the low electrochemical stability in the charging and discharging processes after successive cycles, as demonstrated by the cyclic voltammetry analyses. In order to evaluate the influence of the insertion of conducting polymers in the V2O5 matrix on the electrochemical response, polyaniline and polyethylene oxide were intercalated in the oxide. Despite observing the presence of polymers in the inorganic matrix, it was not noticed an improvement in the electrochemical response of the hybrid materials compared to the matrix, even though the total charge is more stable. In the second synthesis, orthorhombic V2O5, evidenced by XRD and FTIR analyses, was provided by heating assisted by domestic microwave radiation, using pure commercial powder V2O5 as a precursor. The SEM images of the material synthesized for 20 minutes under the action of domestic microwave radiation at a power of 20 W, an excellent material with a homogeneous, porous and uniform structure. From the cyclic voltammograms it was possible to observe a good electrochemical stability and cyclability when compared to the V2O5 of the first mentioned synthesis, in addition to an almost constant total charge during 100 charge and discharge cycles. These results indicate that V2O5 by microwave radiation has a potential for applicability as a cathode in lithium ion batteries.

BANKING MEMBERS:
Externo à Instituição - LUCIANO NADREY MONTORO - UFMG
Externo à Instituição - RODRIGO FERNANDO BIANCHI - UFOP
Externo à Instituição - TULIO MATENCIO - UFMG